Image determining apparatus, image enhancement apparatus, backlight image enhancement apparatus, and backlight image enhancement method

• US 7,916,942 B1
• Filed: 06/01/2007
• Issued: 03/29/2011
• Est. Priority Date: 06/02/2006
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Ohara, Taira
• Primary Examiner(s): Le; Brian Q
• Assistant Examiner(s): Bekele; Mekonen
• Application Number:
  US11/809,907
• Time in Patent Office: 1,397 Days
• Field of Search: 382/162, 382/164, 382/165, 382/168, 382171-173, 382/254, 382/274, 382/275, 382/286, 382/291, 358/1.9, 358/3.26, 358518-523, 358/525, 358/530, 358/1.14
• US Class Current: 382/168
• CPC Class Codes: H04N 1/4074 using histograms
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence

Abstract

Image determining apparatuses, image enhancement apparatuses, backlight image enhancement apparatuses, and backlight image enhancement methods are provided.

Claims

1. An image determining apparatus comprising:

(A) a histogram data generation section that, based on data of pixels constituting an image to be determined, generates data of histograms for each color, the histograms representing a distribution of the number of pixels with respect to density values of each color of those pixels;

(B) an attribute information obtaining section that obtains, for each color, attribute information relating to a first small region and a second small region by partitioning regions represented by the histograms for each color into at least two small regions each, according to the magnitude of the density values, based on the data of the histograms for each color generated by the histogram data generation section, selecting, for each color, as the first small region, a small region whose density values are larger than those of at least one other of the at least two small regions, and selecting, as the second small region, for each color, another small region whose density values are smaller than those of the first small region; and

(C) a determining section that determines whether the image to be determined is an image in which the color balance of the first small region is destroyed, based on the attribute information relating to the first small region for each color and the attribute information relating to the second small region for each color, that have been obtained by the attribute information obtaining section.

2. An image determining apparatus according to claim 1,

wherein the determining section determines whether the image to be determined is an image in which the color balance of the first small region is destroyed, based on the result of a comparison between the attribute information relating to the first small region for each color and the attribute information relating to the second small region for each color, that has been obtained by the attribute information obtaining section.

3. An image determining apparatus according to claim 2,

wherein the determining section determines whether the image to be determined is an image in which the color balance of the first small region is destroyed by comparing a maximum of a first difference between values obtained for each color as the attribute information relating to the first small region for each color and a maximum of a second difference between values obtained for each color as the attribute information relating to the second small region for each color.

4. An image determining apparatus according to claim 3, wherein

the determining section determines whether the image to be determined is an image in which the color balance of the first small region is destroyed, by comparing a third difference between the first difference and the second difference to a predetermined threshold value.

5. An image determining apparatus according to claim 1,

further comprising, in addition to the determining section, a backlight image determining section that determines whether the image to be determined is a backlight image, and

wherein, when it has been determined by the backlight image determining section that the image to be determined is a backlight image, then the determining section determines whether the image to be determined is an image in which the color balance of the first small region is destroyed.

6. An image enhancement apparatus comprising:

(A) a histogram data generation section that, based on data of pixels constituting an image, generates data of histograms for each color, the histograms representing a distribution of the number of pixels with respect to density values of each color of those pixels;

(B) an attribute information obtaining section that obtains, for each color, attribute information relating to a small region by partitioning regions represented by the histograms for each color into at least three small regions according to the magnitude of the density values, based on the data of the histograms for each color generated by the histogram data generation section, and selecting, for each color, at least one small region of the at least three small regions;

(C) a target value obtaining section that obtains a target value for each color of the attribute information relating to the first small region and a target value that is common for all colors of the attribute information relating to the second small region, based on the attribute information obtained by the attribute information obtaining section by selecting, as the first small region, for each color, at least one small region whose density values are smaller than those of at least one other small region, of the at least three small regions, and selecting of the at least three small regions, as the second small region, at least one small region whose density values are smaller than those of the first small region; and

(D) an enhancement processing section that subjects the image to an enhancement process, such that the attribute information of each color of the first small region each becomes the target value for each color, that has been obtained by the target value obtaining section, and such that the attribute information of each color of the second small region each becomes the target value, which is common for all colors, that has been obtained by the target value obtaining section.

7. An image enhancement apparatus according to claim 6,

wherein the attribute information obtaining section obtains, for each color, an average value of the density values of each of the at least one small region as the attribute information,

wherein the target value obtaining section obtains information relating to the luminance for each of the at least one small region, based on the average value of the density values for each color obtained by the attribute information obtaining section, and obtains the target value for each color and the target value that is common for all colors from this information relating to the luminance.

8. An image enhancement apparatus according to claim 7,

wherein the target value obtaining section obtains the average value of the luminance of the pixels for the at least one small region as the information relating to the luminance, and

wherein the target value obtaining section obtains the target value for each color and the target value that is common for all colors, based on a value obtained by adding at least one of the average values of the luminance obtained for the at least one small region and the average value of the luminance of the overall image.

9. An image enhancement apparatus according to claim 6,

wherein the enhancement processing section converts the density values of the respective pixels constituting the image when subjecting the image to the enhancement process,

wherein the enhancement processing section obtains information relating to a correspondence relationship between the density values before the conversion and the density values after the conversion, in order to subject the image to the enhancement process.

10. An image enhancement apparatus according to claim 6,

further comprising a determining section that determines whether the image is an image of a sunset or a sunrise,

wherein the enhancement processing section subjects the image to the enhancement process if the determining section has determined that the image is an image of a sunset or a sunrise.

11. A backlight image enhancement apparatus comprising:

(A) a first determining section that determines whether an image is a backlight image;

(B) a second determining section that determines whether the image is an image in which the color balance of intermediate tones is destroyed, if it has been determined that the image is a backlight image by the first determining section;

(C) a third determining section that determines whether the image is an image of a sunset or a sunrise, if it has been determined that the image is not an image in which the color balance of intermediate tones is destroyed by the second determining section; and

(D) an enhancement processing section that subjects the image to an enhancement process according to a determination result, based on the determination result of the first determining section, the second determining section or the third determining section.

12. A backlight image enhancement apparatus according to claim 11 further comprising:

a histogram data generation section that, based on data of pixels constituting the image, generates data of histograms for each color, the histograms representing a distribution of the number of pixels with respect to density values of each color of those pixels; and

an attribute information obtaining section that obtains, for each color, attribute information relating to a first small region for a first determination and a second small region for a first determination by partitioning regions represented by the histograms for each color each into at least three small regions according to the magnitude of the density values, based on the generated data of the histograms for each color generated by the histogram data generation section, selecting, for each color, as the first small region for the first determination, at least one small region of the at least three small regions, and selecting, for each color, as a second small region for a first determination, a small region whose density values are larger than those of the first small region for the first determination and which is not adjacent to the first small region for the first determination of the at least three small regions;

wherein the first determining section determines whether the image is a backlight image, based on the attribute information relating to the first small region for the first determination for each color and the attribute information relating to the second small region for the first determination for each color, that has been obtained by the attribute information obtaining section.

13. A backlight image enhancement apparatus according to claim 12,

wherein the attribute information obtaining section obtains, for each color, attribute information relating to a first small region for a second determination and a second small region for a second determination by selecting, for each color, as the first small region for the second determination, a small region whose density values are larger than those of at least one small region of the at least three small regions, and whose density values are smaller than those of at least one other small region of the at least three small regions, and selecting, for each color, as the second small region for the second determination, at least one other small region other than the first region for the second determination, and

wherein the second determining section determines whether the image is an image in which the color balance of intermediate tones is destroyed, based on attribute information, for each color, relating to the first small region for the second determination and attribute information for each color relating to the second small region for the second determination, that has been obtained by the attribute information obtaining section.

14. A backlight image enhancement apparatus according to claim 13,

wherein the attribute information obtaining section obtains, for each color, attribute information relating to a first small region for a third determination and a second small region for a third determination by selecting, for each color, as the first small region for the third determination a small region whose density values are larger than those of at least one other small region, of the at least three small regions, and selecting, for each color, as the second small region for the third determination another small region whose density values are smaller than those of the first small region for the third determination, and

the third determination section determines whether the image is an image of a sunset or a sunrise, based on the attribute information, for each color, relating to the first small region for the third determination and the attribute information, for each color, relating to the second small region for the third determination, that has been obtained by the obtaining information obtaining section.

15. A backlight image enhancement apparatus according to claim 13,

wherein the attribute information obtaining section, obtains, for each color, attribute information relating to the small region, by selecting at least one small region of the at least three small regions, and

the enhancement processing section includes an enhancement information generation section that generates enhancement information for subjecting the image to a backlight enhancement process, based on the attribute information, for each color, that has been obtained by the attribute information obtaining section, and subjects the image to the backlight enhancement process, based on the enhancement information generated by the enhancement information generation section.

16. A backlight image enhancement apparatus according to claim 15,

wherein the enhancement processing section selects, for each color, at least one small region, as a selected small region, whose density values are larger than those of one small region and whose density values are smaller than those of another small region, of the at least three small regions, if it has been determined that the image is an image in which the color balance of intermediate tones is destroyed by the second determining section, includes a target value obtaining section that obtains a target value that is common for all colors of the attribute information relating to the selected small region, based on the attribute information that has been obtained by the attribute information obtaining section, and subjects the image to a backlight enhancement process such that the attribute information for each color relating to the selected small region each becomes the target value common for all colors that has been obtained by the target value obtaining section.

17. A backlight image enhancement apparatus according to claim 15,

wherein the enhancement processing section selects, for each color, as a first small region for an enhancement process at least one small region whose density values are smaller than those of at least one other small region, of the at least three small regions, if it has been determined that the image is an image of a sunset or a sunrise by the third determining section, selects as a second small region for an enhancement process at least one small region of the at least three small regions whose density values are smaller than those of the first small region for the enhancement process, includes a target value obtaining section that obtains a target value, for each color, of the attribute information relating to the first small region for the enhancement process and a target value that is common for all colors of the attribute information relating to the second small region for the enhancement process, based on the attribute information that has been obtained by the attribute information obtaining section, and subjects the image to an enhancement process, such that the attribute information for each color of the first small region for the enhancement process each becomes the target value for each color that has been obtained by the target value obtaining section, and such that the attribute information for each color of the second small region for the enhancement process each becomes the target value that is common for all colors that has been obtained by the target value obtaining section.

18. A backlight image enhancement method comprising:

(A) a first step of determining whether an image is a backlight image;

(B) a second step of determining whether the image is an image in which the color balance of intermediate tones is destroyed, if it has been determined that the image is a backlight image;

(C) a third step of determining whether the image is an image of a sunset or a sunrise, when it has been determined that the image is not an image in which the color balance of intermediate tones is destroyed; and

(D) a fourth step of subjecting the image to an enhancement process according to a determination result of the first step, the second step or the third step.